OF ARTS AND SCIENCES. 69 



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tuse, plano-concave, naked ; the proper margin very thin, entire, con- 

 crete, with a thicker, elevated, thalline margin. Graphis inusta, Ach. 

 Syn. p. 85. 



Bark of Prinos verticillata, Canada, Kalm. (Ach.). In this varia- 

 ble genus, long observation is essential to any correct settlement of the 

 species. The present appears to be wholly unknown here. 



XIX. LECANACTIS, Eschw. 



Apothecia immersed, rounded-irregular and lirelteform, always open, 

 the cupular, carbonaceous, proper exciple connate with the thallus, 

 which constitutes sometimes an accessory margin. Disk horny, some- 

 what plane, never connivent, veiled at first by the pruinose thallus, and 

 bordered by the erect margin of the exciple. Thallus crustaceous. 



L. impolita, Fr. Cr. tartareous, contiguous, chinky, glaucescent ; 

 apolh. immersed, dilated, maculseform, obscurely fuscous, glaucous- 

 pruinose. Fr. Samm. Fl. Scand. Arlhonia, Borr. in E. Bot. Suppl. 

 t. 269^. Parmelia, Fr. Lichenogr. p. 183. Lichen, Ehrh. Arthonia 

 pruinosa, Ach. 



Trunks. Pennsylvania, Muhl. 



Tribe IV. CALICIACE^, Fr. 



XX. TRACHYLIA, Fr. 



Apothecia sessile, discrete from the thallus, orbiculate. Disk some- 

 what compact, ascigerous, margined by the innate, carbonaceous, proper 

 exciple, or the exciple obsolete. Asci oblong. Thallus crustaceous. 



This genus, for which I am not able to furnish a complete character, 

 is distinguished from the other genera of the tribe by the sporidia being 

 contained in asci. Several of the species have also a peculiar habit, 

 quite different from that of the true Calicia. 



1. T. tigillaris, Fr. Crust areolate-verrucose, bright greenish-yel- 

 low ; apothecia innate ; the disk originally naked, black, equalling the 

 tumid margin. Caliciiun, Turn. ^' Borr. Lich. Brit. p. 132. Fr. Li- 

 chenogr. p. 400. Trachylia, Fr. Summ. Fl. Scand. 



Old rails and pales, and also on trunks. New England. New 

 York, Halsey. Arctic America, Rich. 



